The invention relates to the field of intraluminal catheters, and particularly to guiding catheters suitable for intravascular procedures such as angioplasty, stent deployment, pacing lead deployment and the like.
In percutaneous transluminal coronary angioplasty (PTCA) procedures a guiding catheter having a shaped distal section is percutaneously introduced into the patient's vasculature and then advanced through the patient's vasculature until the shaped distal section of the guiding catheter is adjacent to the ostium of a desired coronary artery. The proximal end of the guiding catheter, which extends out of the patient, is torqued to rotate the shaped distal section and, as the distal section rotates, it is guided into desired coronary ostium. The distal section of the guiding catheter is shaped so as to engage a surface of the ascending aorta and thereby seat the distal end of the guiding catheter in the desired coronary ostium and to hold the catheter in that position during the procedures when other intravascular devices such a guide wires and balloon catheters are being advanced through the inner lumen of the guiding catheter.
In the typical PTCA or stent delivery procedures, the balloon catheter with a guide wire disposed within an inner lumen of the balloon catheter is advanced within the inner lumen of the guiding catheter which has been appropriately positioned with its distal tip seated within the desired coronary ostium. The guide wire is first advanced out of the distal end of the guiding catheter into the patient's coronary artery until the distal end of the guide wire crosses a lesion to be dilated or an arterial location where a stent is to be deployed. A balloon catheter is advanced into the patient's coronary anatomy over the previously introduced guide wire until the balloon on the distal portion of the balloon catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated with inflation fluid one or more times to a predetermined size so that in the case of the PTCA procedure, the stenosis is compressed against the arterial wall and the wall expanded to open up the vascular passageway. In the case of stent deployment, the balloon is inflated to plastically expand the stent within the stenotic region where it remains in the expanded condition. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation or stent deployment but not overexpand the artery wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter and the guide wire can be removed therefrom. Generally, the stent deployment may be accomplished simultaneously with or after a PTCA procedure has been performed at the stenotic site.
In addition to their use in PTCA and stent delivery procedures, guiding catheters are used to advance a variety of electrophysiology-type catheters and other therapeutic and diagnostic devices into the coronary arteries, the coronary sinus, the heart chambers, neurological and other intracorporeal locations for sensing, pacing, ablation and other procedures. For example, one particularly attractive procedure for treating patients with congestive heart failure (CHF) involves introduction of a pacing lead into the patient's coronary sinus and advancing the lead through the patient's great coronary vein and a branch of the great coronary vein until the distal end of the pacing lead is disposed at a location which allows the electrical impulses from the pacing lead to pace the left ventricle of the patient's heart. A second pacing lead may be disposed within the patient's right ventricle or a cardiac vein draining the patient's right ventricle and both the left and right ventricle may then be paced by the pacing leads, resulting in greater pumping efficiencies and greater blood flow out of the heart which minimizes the effects of CHF.
Current construction of many commercially available guiding catheters include an elongated shaft of a polymeric tubular member with reinforcing strands (usually metallic, high strength polymers or combinations thereof) within the wall of the tubular member. The strands are usually braided or wound into a reinforcing structure. The desired shape in the distal section of the catheter, which facilitates its deployment at the desired intracorporeal location such as the coronary sinus, is typically formed by holding the distal section in the desired shape and heat setting the polymeric material in the distal section of the catheter wall to maintain the desired shape. There is usually some spring-back after the heat formation due to the reinforcing braid, but this is usually compensated for in the shape the catheter is held in during the heat setting.
The current guiding catheter shafts also have outer polymer jackets with radiopaque fillers embedded in the resin. Clinical requirements for utilizing guiding catheters to advance catheters and other intravascular devices have resulted in a need for increased transverse dimensions of the inner lumens of guiding catheters to accommodate a greater variety of large intracorporeal devices with little or no increase in the outer transverse dimensions of the guiding catheter to present a low profile which facilitates advancement within the patient's body lumens and openings. These catheter design changes have required a reduction in the wall thickness which in turn requires the outer polymer jacket to be thinner on the wall. The combination of the thin wall polymer jacket along with large amounts of radiopaque fillers such as bismuth, bismuth oxychloride and tungsten may cause the outer polymer jacket to split or break during torsional movement. When the radiopaque filler ratio exceeds the polymer resin ratio, the outer polymer jacket has lower ductility which causes the splits and tears. Reduction of wall thickness also translates into a reduction in the ratio of polymer to stranded reinforcement and/or a reduction in strand thickness. These factors result in a catheter shaft which may not have the requisite mechanical properties such as torqueability or kink-resistance.
What has been needed is a catheter design which would allow for continued thinning of the catheter wall for increased lumen size in conjunction with low outer profiles, improved radiopacity, while providing the mechanical and physical properties that are clinically desirable for such products, and preventing tearing, cracking, bend kinks and torsional breaks in the outer jacket of the catheter. The present invention satisfies these and other needs.